Today's mobile communication devices, including mobile phones, are multi-mode (2G, 2.5.G, 3G, 4G, LTE) multi-band (Band I, II, V, VII, etc.) devices. The transmit and receive circuitry of each mobile communication device must be calibrated and tested during fabrication in order to verify that the devices meet the standardization requirements as defined by the mobile communication standardization bodies, the phone manufacturers and the wireless network operators. Furthermore, advanced testing techniques are used to lower the probability that a fabricated mobile device component and/or the resulting fabricated mobile device is not returned to the manufacturer as defective.
Testing of mobile communication circuitry may be performed on the transmit chain of the mobile device communication circuitry to test the Error Vector Magnitude (EVM), Adjacent Channel Power Ratio (ACPR), the transmit power and the modulated spectrum at various frequency offsets to name a few. These tests are used to determine whether the transmission chain(s) are operational, as well as whether the transmission chain(s) are operating within government and industry defined parameters and limitations. The EVM is a quantification measurement used to quantify the performance of a digital radio transmitter or receiver. For example, an EVM is the quantification of the difference between the actual received symbols and ideal symbols.
Presently, very expensive external test equipment is connected to or probes the antenna output node of the mobile device radio circuitry to perform such transmit chain testing. Once connected, it takes a significant amount of time to set up the external test equipment, to program the mobile device radio circuitry, set up the test, set up the receiving test equipment to be calibrated and to read the expected signal, to run each test, process the data for each test, and finally to make a determination as to whether the circuit under test passed or failed the battery of tests.
Referring to FIG. 1, a transmit chain test set up using external test and measurement equipment is depicted. The mobile device 10 that comprises a multitude of components is shown. For simplicity, only a few of the many components that may exist within a mobile device 10 are depicted. One of ordinary skill in the art would understand that additional circuitry and elements are found in a mobile device 10. A Front End Module (FEM) 12 is shown being connected to the radio circuitry 14. The FEM 12 is a separate chip or circuit from the radio circuitry 14. The radio circuitry 14 is basically divided into two portions being receiver circuitry 16 and transmitter circuitry 18. The transmitter circuitry 18 may have a plurality of transmission chains 20, 22. Each transmission chain may be designated for a specific operating band. For example, transmission chain 20 may be designated for transmitting in the Band II frequency domain, which transmits channels between the 1850 to 1910 megahertz. Meanwhile, transmission chain 22 may be for transmitting Band VIII, which transmits channels (having about a 0.2 megahertz width) between the frequencies of 880 to 915 megahertz.
The receiver circuitry 16 similarly may have a plurality of receiver chains 24, 26. Receiver chain 24 may be for receiving channels within Band II, which will be between 1930 to 1990 megahertz. Receiver chain 26 may be designated for receiving channels within frequency Band VIII, which is between 925 to 960 megahertz.
The Digital Baseband (DBB) block 28 receives a down converted modulated carrier or baseband signal and may be used to convert the received baseband signal to data that can be used by other circuitry within the mobile device. For example, the DBB block may convert a received baseband signal into text messages or digital audio data to be used by other circuitry within the mobile device (not specifically shown). The digital baseband block 28 may comprise a plurality of microprocessors and other circuitry to create or decode digital baseband transmission and reception signals sent over a selected transmission chain band or received via a specific receiver chain band.
For simplicity and for better understanding only two transmitter chain circuits 20 and 22 are depicted in FIG. 1. It is understood that there may be a plurality of transmitter chains in the transmitter circuitry 18. Furthermore, only two receiver chains 24, 26 are depicted in the receiver circuitry 16. It is further understood that additional receiver chains may exist in exemplary embodiments of the invention.
To test, for example, transmitter chain 20 a relatively inexpensive computer or PC set-up device 30 may be connected via a data bus 32 to the mobile device 10, or in particular, to the DBB block 28. The PC test set-up device 30 operates in conjunction with the external test and measurement equipment 34. The external test and measurement equipment 34 is typically
an extremely expensive piece of equipment (can cost in the hundreds of thousands of dollars) that is adapted to measure power, perform frequency analysis, measure power in the frequency domain and to demodulate the modulated carrier to compute EVM, ACPR (Adjacent Channel Leakage Power Ratio) and the modulated spectrum of a transmit signal. The external test and measurement equipment 34 is connected to an antenna node 36 via a probe or other connection 38. The antenna node 36 is located on the FEM chip or circuit where a mobile device antenna would normally be connected, but testing of the transmit chains of a mobile device's circuitry is normally done prior to the connection of an antenna to the antenna node 36.
The PC set-up device 30, via the bidirectional bus 32, sets the FEM 12 to switch the Antenna Switch Module (ASM) 40 such that the output of the power amp 42 in the transmitter chain 20 is connected to the antenna node 36, via input node 41, so that the modulated carrier signal originating from the Band II transmit chain circuitry 20 can be read by the probe connection 38 of the external test and measurement equipment 34. The modulated carrier goes through the ASM 40 directly to the external test and measurement equipment 34 via the probe connection 38. The PC test set-up device 30 informs the external test and measurement equipment 34 that it will be testing a first channel in Band II via transmitter chain 20. The external test equipment 34 then configures itself via switches, communication pipes and settings to receive the designated channel of the designated band so that test measurements can be taken and recorded. After test measurements are recorded, the PC test set-up device 30 may inform the external test and measurement equipment 34 that it will now be testing a different channel of Band II via the transmitter chain 20. Again, the external test and measurement equipment must recalibrate itself and adjust to receive and measure the signal of the next test. This process continues until the multitude of tests needed to be performed on the various transmitter Band chains 20, 22 (and others not specifically shown) are completed.
This technique of testing transmission chains provided from a digital baseband block 28, transmitter circuitry 18, FEM circuitry 12, and an external test and measurement device requires that a multitude of connections, relays communication pipes and programming of the additional expensive test and measurement equipment 34 be incorporated into every test of every mobile communication device. Thus, using the external test and measurement equipment 34 is a relatively inefficient technique for testing the multitude of transmission chains within the circuitry of a many mobile devices during their fabrication. Again, the external test and measurement equipment 34 may cost several hundred thousand dollars to purchase and furthermore requires costly ongoing maintenance and calibration.
The external test and measurement equipment 34 tests the EVM, the ACPR, or ALCR the modulated spectrum and other parameters for each 2G and 2.5G Band to determine whether the device under test is transmitting within predetermined range limits and determines whether the device under test passes or fails. If the mobile device circuitry fails, it is removed from the fabrication line and if it passes it continues on to potentially be incorporated into a completely fabricated mobile device.
It should be understood that a Band is defined per the U.S. Federal Communications Commission (FCC) definitions. For example, transmit Band II is defined by a plurality of channels that are between two frequencies. For the transmit Band II, the plurality of channels are between 1850 megahertz and 1910 megahertz. In 2G and 2.5 G communication each channel within a Band has a bandwidth of about 0.2 megahertz. Therefore there can be about 100 channels within, for example, transmit Band II. Realistically, it would take too long to test all the channels within each of the 2G or 2.5G Bands. Thus, what is normally done is a test on a lower frequency channel, a mid frequency channel and a high frequency channel within each transmit Band in order to increase the probability that the transmitter chain for the specific transmit band operates properly for all the channels within that transmit Band. This is done for each 2G and 2.5G transmit chain in the transmitter circuitry portion 18 using the external test and measurement equipment 34. Presently, there are five operating bands for 2G and 2.5 G communications. These Operating Bands are Bands II, III, V, VI and VIII, which each have a transmit frequency range and a receive frequency range as depicted in Table 1 below.
TABLE 12 G and 2.5 G frequency bandsOperatingUL frequenciesDL frequenciesBandUE transmit, node b receiveUE receive, Node B transmitII1850-1910 MHz1930-1990 MHzIII1710-1785 MHz1805-1880 MHzV824-849 MHz869-894 MHzVI830-840 MHz875-885 MHzVIII880-915 MHz925-960 MHz
Thus, what is needed is a less expensive and less time consuming method of testing the transmission chain Bands of a mobile device's radio circuitry. Such a solution could remove the need for purchasing and maintaining very expensive external test equipment, would decrease the amount of time required to test each mobile device radio's transmission chain, and would ultimately decrease the overhead cost of testing mobile device circuitry.